[en] The paper draws on the survey led on 2.500 walloon people in collaboration with IWEPS in 2003-2004. It studies the impact of the belgian law that makes voting compulsory. If it was no longer teh case, who would go on voting ? Results of the survey shows that the constituency would differ rather strongly from what it is now : in particular, amnong the poor people and the less educated would many would drop voting. But it would be the case too of lonely people, for instance or people who feel unsecure. The result would be that the specific demands form those categories would loose much weight in the political process.